128 J. T. Jittson : Lake Goongarrie. 



Where the '' high " lands abut directly on to the lake, the sancJ 

 ridges and arms may be unconnected with the " lowlands." 



Westwand Migration of the Whole Topographic 



System. 



It would appear, thercfoie, that the " lowlands " originally 

 extended farther east, but by the processes above described, strips^ 

 have been removed to at least partly form the sand ridges, and, by^ 

 such removal, the arms of the lake have been formed and the bed- 

 rock planed down. The process is still apparently going on, the* 

 arms, and probably the sand ridges, extending westward, while 

 bedrock at the eastern ends of the sand ridges is being planed to a 

 level rock floor. The " lowlands " are being removed at their 

 eastern side but the western side is extending westward by the- 

 wearing away of the low tableland and connecting cliffs. The heads' 

 of the drainage lines are cutting back westward, and such 

 lines are being obliterated in their lower portions by the westward 

 advance of the lake rock floors. As the latter grow westward the- 

 silt will tend to spread over them, hence the silt floors are probably 

 extending westward, and they, in turn at their eastern margin ^ 

 appear to be encroached upon by the sands. 



Thus there seems to be a westward migration of practically the- 

 whole system, rock cliffs, rock floors, the lake itself (including the 

 eastern and western shores), the lake arms, the sand ridges, the- 

 " lowlands," and the silt floors. If this conclusion be correct, it 

 shows how portions of the country are being laterally planed away 

 at a comparatively high level, and as wind is regarded as the 

 governing factor, it also shows what an important part it is playing 

 in the shaping of the land surface. 



